High field effects in chalcogenide thin films

Current vs. voltage characteristics of thin films made of Te-As-Ge-Si-type chalcogenide glass have been measured at various temperatures. It has been found that two types of field dependence occur. At electric fields above 10 4 V/cm there is Poole-Frenkel emission. At fields above 5 × 10 5 V/cm a stronger field dependence occurs. At low temperatures this can be explained by tunneling of electrons from traps to the conduction band and from the valence band to traps, respectively. A gaussian trap distribution in the mobility gap was used in analyzing the high field currents measured. The measurements of current vs. voltage characteristics have been supplemented by measuring thermally stimulated current.